Conventionally, there has been known an optical device in which an optical element is hermetically sealed so as to suppress an influence of humidity or the like on the optical element.
For example, Patent Literature 1 discloses a configuration in which an MEMS mirror is hermetically sealed. According to the configuration, in a state where the MEMS mirror which serves as an optical element is provided in a casing, the casing and a lid are connected to each other by a connecting material made of resin.
Patent Literature 2 also discloses a configuration in which a micro-mirror array device is hermetically sealed. According to the configuration, in a state where the micro-mirror array device which serves as an optical element is provided in a package substrate, the package substrate is soldered to a cover substrate via a sealing medium layer.